But the Riveras say they shudder to think what might have happened to their little girl by now if they had accepted the verdict of a doctor they met with in early 2012. They say that doctor, from a leading children's hospital, told them that even though Amelia's kidneys were failing, she was a bad candidate for a transplant – because she was "mentally retarded."

Amelia, who has a rare genetic condition called Wolf-Hirschhorn syndrome, does have intellectual disabilities, along with various physical problems. But the Riveras found it shocking and unacceptable that her mental capacity could determine whether she lived or died.

So Chrissy did something that turned Amelia's case into a cause: She went to a website usually seen only by others in the small Wolf-Hirschhorn community and wrote about that encounter at Children's Hospital of Philadelphia (CHOP). "I expected it to be seen by 10 or 20 people," Chrissy says. Instead, it went viral and inspired some 50,000 people to sign a petition at Change.org, demanding that the hospital allow the transplant. Newspaper stories and blog posts were written. Medical ethicists weighed in — and generally agreed that although transplant centers had to consider patients' overall health and ability to thrive, it wasn't right for anyone to be denied just because they had a mental handicap.

Within days, Chrissy says, several members of the Philadelphia hospital's ethics committee were in her living room. A few weeks later, the family and the hospital released a joint statement saying a transplant was under discussion. Hospital officials apologized for what had happened, while saying it was never their policy to deny transplants on the basis of intellectual ability.

Later, the family announced that Chrissy had qualified as Amelia's donor. The surgery was done July 3. The Riveras say they are very happy with the care Amelia has received. The family declined to discuss how the surgery was paid for.

In a statement Friday, the hospital said: "We appreciate the role the Riveras have played in helping us recognize opportunities for improvement and believe we are a better institution as a result. We look forward to providing Amelia and her family the very best of care long into the future."

But that happy ending does not mean that the fight Amelia inspired is over.

In the months since Amelia's story became public, Chrissy says, "a lot of people have reached out to us personally to share similar stories, to tell us heartbreaking stories of how their loved ones were denied simple medical care, dental care, eye glasses — because medical professionals felt that this person's quality of life wasn't good enough to get this care."

They say even before the transplant fight they often had to demand such basic care for Amelia. So they want to speak up now for others facing those barriers.

In that spirit, Chrissy Rivera recently went to New York City to speak at a dinner hosted by Special Olympics at the annual meeting of the Clinton Global Initiative.

"I don't have a concrete solution to change the stigma that exists in the medical community," she told that gathering.

STANDARD OF CARE

According to a 2009 report from the federal Centers for Disease Control and Prevention, the health of people with intellectual disabilities has not been adequately studied, but existing research suggests they do get poorer health care and have poorer health than the rest of the population. Research compiled by Special Olympics suggests that the unwillingness of some doctors to treat people with such disabilities continues to play a role in the gap.

But Amelia's story already is making a difference, says Tim Shriver, chairman of the board and CEO of Special Olympics.

"It has awakened people who didn't see the issue before," he says. Her name has come up, he says, in meetings he's attended with medical leaders and government officials who want to address the problem. The gap exists partly because of a lack of training for medical professionals but also because of "old fashioned ignorance and stigma," he says.

"Chrissy is a hero," he says, for speaking up for her daughter and for others.

How long Amelia will continue to thrive is uncertain. She goes to a clinic once a week for a checkup and shows no sign of rejecting her new kidney — though her parents understand that it likely will fail some day. They have been told a typical transplanted kidney lasts 12 years. Luckily, they say, Joe also is a match for her. But Amelia does have other medical issues: She is not able to eat on her own, so she gets nourishment through a tube in her stomach; she also needs to take medications to prevent seizures and treat asthma. She is more vulnerable to infections than most people.

Chrissy and Joseph Rivera with daughter Amelia, then 3, in January 2012, before her kidney transplant.(Photo: Mel Evans, AP)

The life expectancy for people with Wolf-Hirschhorn syndrome today is unknown, but it is known that some individuals with the syndrome survive into their 30s, 40s and beyond, says the National Institute of Health's Office of Rare Diseases Research.

ONE DAY AT A TIMEFor now, Amelia's parents are focused on raising a little girl. Amelia is not yet healthy enough to go to school, but she works with a teacher and therapists at home. She enjoys bedtime stories from her two brothers, her parents say. She does not walk, but gets around a bit by rolling on the floor. She does not speak, but does communicate, Chrissy says: "She definitely lets us know when she is happy or unhappy."

Some children with Amelia's syndrome do eventually learn to walk and talk, but what developmental progress Amelia makes, on what timetable, is not a big worry, Chrissy says: "Amelia is going to write her own book; she is going to meet her own milestones when she is ready."